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Home » Cycling » Top Speeds And Understanding Road Cycling Gear Combinations: The Compact Double, The Pro Compact, And The Big Dog 53/39 Pro Chainset Compared and Contrasted

Top Speeds And Understanding Road Cycling Gear Combinations: The Compact Double, The Pro Compact, And The Big Dog 53/39 Pro Chainset Compared and Contrasted


For this post I won’t be looking into the newer, smaller large chainrings. Truthfully, with the exception of gravel riding, I think they’re useless – especially when you pair a 48 tooth big ring with a 35 tooth little ring. Why, when you can have a perfectly fantastic 50/34 compact combo, would anyone ever pick something that has less high-end and low-end speed?! It makes absolutely no sense to me when you consider that on a road bike we want to keep the cassette cog size jumps to a minimum. And if you go with a 46, without a 10 tooth cassette cog you’ll surely gear out in a halfway decent sprint. Not ironically, some people will think I’m nuts – and that is perfect! Because that’s how you know all is well in cycling. If everyone agrees, Houston, we have a problem.

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Let’s get our hands dirty. I used to think the upper escape velocity limit for a compact double (50/34 chainset) with an 11t big gear was 40-mph. Escape velocity is the speed at which you can’t pedal faster to make the bike go faster – you’re geared out. Used to being the operative portion of that second sentence. One of my favorite rides has a straight shot descent down an 8% hill on good asphalt and my wife and I rode the route with a couple of friends a while back. I can tell you, with utter certainty, with a 50 tooth chain ring and the small 11 tooth cog on the cassette, you can reach 45-mph pedaling:

45mph_MS

I can also tell you, the upper limit of a 52/11 combo is about 53-mph. I can also, also tell you, at 45-mph with a 50 and 53-mph with a 52, your legs are going to be pumping!

So this will properly lead to the question (and subsequent discussion), how much gear is really necessary when you’re looking at recreational road cycling?

In order to really break this down properly, we’re going to have to classify us some road cyclists. Starting from slow to fast, you’ll have the recreational cyclist, the enthusiast, the avid enthusiast and the pro cyclist. Within those four categories, we should be able to pigeon hole everyone into gearing that will suit their needs.

For the recreational road cyclist, and we’ll lump gravel in here, too (and smaller chainrings do work for gravel, as do 1x drivetrains), you won’t need anything more than a 50/34 compact. In fact, with cassette choices, anything more than a compact is a waste of gearing. For you, because you’re a special breed of cyclist, the 48 and even the 46 can be a good big chainring for you. For the recreational cyclist, gearing out is usually not an issue.

For the enthusiast, the 50/34 chainset is a good combination. Fitted with a decent 10, 11, or 12-speed cassette on the back, you’ll be able to go just about anywhere the road takes you. My favorite cassette with the compact is the 11-28. Enough high-end to get you to 45-mph and enough low end to get you up a 25% grade. That’ll do.

For the avid enthusiast, where I reside, it’s going to be a tossup between the 52/36 pro compact and the 50/34 compact. I happily rode with a 52/36 on my good bike and a 52/42/30 triple on my rain bike for years. Then, I decided to try the 50/34 on a whim, when I swapped out the drivetrain on the rain bike and I chose the 11/28 cassette over an 11/26… I liked the 11/28 so much I put one on the good bike as well, and that’s where I saw the flaws in the 52/36 combo – there were massive cadence holes between gears at the exact speeds I liked to ride – between 18-1/2 and 22-1/2-mph. Between that 4-mph stretch, I felt like I was in the wrong gear – either too easy or too hard… I went back to an 11/25 and was happier, until I ran out of gears on the way up a hill, but that was rare. After last season, I decided to change the Venge to a 50/34, simply by changing chainrings – it cost me all of $75 for a couple of SRAM Force rings:

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Sure, I lost a little in top-end speed, but what 50-year-old (or almost 50-year-old) needs anything more than 45-mph anyway?! I can’t get that fast without a downhill, anyway! I’ve only ever been above 50 a few times (45-mph = 72-km/h, 50 = 80 km/h) so the 52/11 was really a wasted gear. I gained a bunch for climbing with the new combo, though. I can climb anything Michigan can throw at me, including easily climbing a nice 22% monster in Sleeping Bear Dunes National Park. On the other hand, the 52/36 with an 11/25 or 26 cassette worked just fine for anything up to 18%.

Lastly, we’ve got our amateur racers and pros – those who actually choose a cassette to fit the conditions they’ll be riding in. Flat? They’ll be going with a corncob 11/23 cassette. A little climby? 11/25, maybe 11/28 (many pros use the 11/28 – the cadence holes are at speeds below their normal pace). The two chainring combinations of choice are the 53/39 and the 52/36 – except for the pros who dabble in the bigger combos. Peter Sagan’s 55/42 on his sprint bike, for instance.

The point is, it appears to me you really have to be in the upper crust to need more than a 50 tooth big ring and 34 tooth little – and as avid as I am about cycling, there’s no question the 50/34 is an easy favorite. It’s got everything I need and is almost as good as my old 52/42/30 triple… and without all of the gear overlap and the finicky nature of a triple.


10 Comments

  1. The Omil says:

    All good sense – and as you get older but still like big hills, you appreciate the benefit of 50/34 and 11/32

  2. unironedman says:

    Whenever I hear this chat, I think of this:
    “Sean Kelly was also a formidable descender, clocking a career top race speed of 124 km/h, while descending from Col de Joux Plane to Morzine on stage 19 of the Tour in 1984…”

  3. I will happily admit I don’t have the legs for anything bigger than a 50T. If I’m spinning out in 50/11 that’s fast enough for me. My new aero bike came with a 52/36, but I switched it out for a 50/34 that day I built it up!

    • bgddyjim says:

      I used to think the 52/36 was the bees knees until I tried an 11/28 cassette. Before that, I’d always used an 11/25 (Shimano) or 11/26 (SRAM) because we don’t have much in the way of climbing around here. With traveling, I needed that last 28 cog to get up the monsters and that changed everything. I agree with you… I think the compact is a much better option for guys like us.

  4. 50/34 is my favourite too.

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